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Biomedical subjects

A Bengtsson

Publications and source records attributed to A Bengtsson.

At least 109 records · Page 6Linked to original sources
PubMed1994

Nitrous oxide uptake during spontaneous and controlled ventilation.

The rate of uptake of nitrous oxide was studied in 40 orthopaedic patients anaesthetised with either enflurane or isoflurane in nitrous oxide and with either spontaneous or controlled ventilation. A variant of the Douglas bag method was used in combination with low fresh gas flows to a circle system. There were no significant differences in nitrous oxide uptake between the groups and the uptake rates followed 'the square root of time concept', with an overall best fit curve of 1080.t-0.505 ml.70 kg-1 x min-1. During spontaneous ventilation, the nitrous oxide uptake rate was similar or even higher than the corresponding rate during controlled ventilation, in spite of lower minute volumes.

Adult↗
PubMed1994

Predictable nitrous oxide uptake enables simple oxygen uptake monitoring during low flow anaesthesia.

The uptake rate of oxygen and nitrous oxide were studied during low flow anaesthesia with enflurane or isoflurane in nitrous oxide with either spontaneous or controlled ventilation. The excess gas flow and composition were analysed. The nitrous oxide uptake rate was in agreement with Severinghaus' formula VN20 1000.t-0.5. The composition of excess gas was predictable and the following formula for oxygen uptake could be derived: VO2 = VfgO2-0.45 (VfgN2(0)-(kg: 70.1000.t-0.5)) where oxygen uptake rate (VO2, ml.min-1) equals oxygen fresh gas flow (VfgO2) minus 0.45 times the difference between the fresh gas flow of nitrous oxide (VfgN2O), ml.min-1 and estimated uptake of nitrous oxide. The equation assumes constant inspired gas concentrations of 30% oxygen and 65-70% nitrous oxide. The oxygen uptake rates calculated from this formula were in good agreement with measured uptake rates. Thus, continuous monitoring of oxygen uptake rates is possible by using only reliable flowmeters and analysis of inspired oxygen concentration.

Adult↗
PubMed1993

Sampled gas need not be returned during low-flow anesthesia.

OBJECTIVE: The purpose of this investigation was to study the N2 flux between the patient and the breathing circuit, and the excess gas during N2O anesthesia with the low, fresh gas flow technique. METHODS: Forty patients were studied. After a 6-minute high, fresh gas flow denitrogenation period, the O2 fresh gas flow was set at about 4 ml/kg/min and the N2O fresh gas flow was set to maintain an inspired O2 fraction of 0.30. The excess gas flow and N2 excretion were measured by a variant of the Douglas bag method. RESULTS: The mean inspired N2 concentration reached a peak of 5.9% at 40 minutes. The estimated mean N2 excretion was 39 ml/min at 10 minutes, declining to 18 ml/min at 60 minutes. A calculation of N2 homeostasis during closed-circuit anesthesia based on the results of the patient study indicated that sampling for gas analysis actually reduces the gas costs if the sampled gas is scavenged instead of returned to the circle system, since intermittent flushing with high, fresh gas flow for denitrogenation is unnecessary in the former situation. CONCLUSIONS: Regardless of the fresh gas flow used, sampled gas need not be returned during N2O anesthesia.

Adult↗
PubMed1993

Hemofiltration modifies complement activation after extracorporeal circulation in infants.

Complement and fibrinolytic factors were measured in 9 infants undergoing hemofiltration immediately after cardiopulmonary bypass in an attempt to reduce activation of these systems. Plasma levels of C3a, C5a, and terminal complement complexes increased during bypass by 460%, 85%, and 745%. Plasma levels were reduced after hemofiltration in 8 of the 9 infants, and C3a and C5a fractions were recovered in the ultrafiltrate. The observed activation of the fibrinolytic system seemed to be unaltered by hemofiltration. Fibrinolytic factors were not filtered. Our study shows that increased concentrations of complement factors in the plasma after bypass in infants may be reduced by hemofiltration.

Complement Activation↗
PubMed1993

Nitrous oxide elimination and diffusion hypoxia during normo- and hypoventilation.

We studied the elimination rate of nitrous oxide in 36 patients undergoing orthopaedic surgery. They were allocated randomly to one of six groups which differed in time of nitrous oxide exposure and mode of ventilation. In order to simulate recovery conditions, nitrous oxide administration was discontinued after 30, 60 or 120 min of exposure. Either normoventilation or hypoventilation was used. The mean excretion rate was 1 litre min-1 at 1 min, declining to 100 ml min-1 at 30 min, with relatively small effects of different modes of ventilation and times of exposure. In spite of an FIO2 of 0.30, there were significant decreases in SpO2 during both normo- and hypoventilation. The smallest end-tidal oxygen concentrations were reached at 10-15 min in the groups with hypoventilation, after 1 or 2 h of nitrous oxide exposure.

Adolescent↗
PubMed1993

Complement activation during liver transplantation.

Twelve patients with end-stage liver disease undergoing liver transplantation were studied regarding complement activation and formation of anaphylatoxins (C3a and C5a) and terminal C5b-9 complement complexes (TCC) after reperfusion of the grafted liver. Blood samples for complement variables (C1INH, C3, C4, C5, C3a, C5a, and TCC) were drawn preoperatively, before the anhepatic phase, 1 min before, and 2, 15, and 60 min after the start of reperfusion of the grafted liver. Activation of complement was observed during the operation. The C1INH, C3, C4, and C5 plasma concentrations decreased during the entire operation while the anaphylatoxin C3a and the terminal C5b-9 complement complex increased after the reperfusion of the grafted liver. Activation of complement with the formation of biologically active substances like anaphylatoxins and terminal C5b-9 complement complexes may be one explanation for circulatory complications often seen in patients undergoing orthotopic liver transplantation.

Adult↗
PubMed1993

Complement activation in septic baboons detected by neoepitope-specific assays for C3b/iC3b/C3c, C5a and the terminal C5b-9 complement complex (TCC).

We have investigated the cross-reactivity of various species in neoepitope-specific methods for quantification of human complement activation products. In contrast to most other species examined, baboon showed a substantial cross-reactivity supporting a high degree of homology between human and baboon complement. An assay for C3b, iC3b and C3c (MoAb bH6) showed moderately good reactivity, in contrast to a C3a assay which did not cross-react. Excellent reactivity was found for C5a using MoAbs C17/5 and G25/2. The reactivity of an established TCC assay (MoAb aE11 to a C9 neoepitope and polyclonal antibody to C5) was improved substantially by replacing the anti-C5 antibody with a new MoAb to C6 particularly selected on the basis of baboon cross-reactivity. Plasma samples from baboons receiving 2.5 x 10(9) and 1.0 x 10(10) live Escherichia coli bacteria/kg were examined with the assays described. In vivo complement activation with the lowest dose was moderate and kept under control, in contrast to the highest dose, where an uncontrolled increase in all activation products continued throughout the infusion period. These results support the hypothesis that sufficiently high amounts of endotoxin lead to uncontrolled activation of complement as seen in irreversible septic shock. The results are discussed with particular emphasis on activation of the terminal complement pathway.

Animals↗
PubMed1993

Cascade system activation in shock.

Trauma and sepsis activate different cascade systems. Activation of the coagulation and clotting systems, of the kinin-kallikrein system and of the complement system are important etiological mechanisms behind development of the adult respiratory distress syndrome (ARDS) and multisystem organ failure (MOF) after extensive trauma or severe septic situations. Activation of complement with the release of anaphylatoxins and terminal complement complexes is associated with increased mortality and development of ARDS and MOF after major surgery and in situations of septic shock. The anaphylatoxins have potent vascular properties and they activate leukocytes. Their effects on the leukocytes lead to the release of free oxygen radicals, different lysosomal enzymes and cytokines, leukotrienes and histamine. All these inflammatory mediators may, if released in extensive amounts, induce microvascular injury and interstitial edema. If this process takes place in the lung, ARDS may develop and if other organs, i.e the liver and the kidneys, are involved, MOF may be the result.

Complement Activation↗
PubMed1993

[Respiratory gas exchange. Anesthesia with enflurane or isoflurane in nitrous oxide during spontaneous and controlled ventilation].

The estimation of oxygen consumption and carbon dioxide elimination is essential for predicting the metabolic activity and needs of any patient having anaesthesia. During anaesthesia oxygen consumption can be measured and compared to a predicted value. However, oxygen uptake is affected by anaesthetic agents, which complicates the interpretation of measured oxygen uptake rate. The purpose of this study was to investigate whether there are any differences in respiratory gas exchange during anaesthesia with enflurane and isoflurane and also to assess the effects of spontaneous versus controlled ventilation. METHODS. Forty orthopedic patients were randomized to enflurane or isoflurane anaesthesia in nitrous oxide with either spontaneous or controlled ventilation. A fresh low-gas-flow technique was used. Inspiratory oxygen and end-tidal carbon dioxide concentrations and expiratory minute ventilation were measured in a circle absorber system between the y-piece and the endotracheal tube with a sampling analyser. Between the mixing box and the absorption canister, carbon dioxide concentration was continuously measured. The carbon dioxide elimination was calculated from mixed expired concentration and expiratory minute ventilation. Excess gas was collected every 10 min in a non-permeable mylar plastic bag connected to the excess valve. The excess gas flow was calculated and the oxygen uptake rate was assumed to be the difference between the oxygen fresh gas flow and the oxygen excess gas flow. RESULTS. The grand mean oxygen uptake rate was 2.5 ml.kg-1 x min-1 or 100 ml.min-1 x m-2. There were no statistically significant differences in oxygen uptake between enflurane and isoflurane anaesthesia or between spontaneous and controlled ventilation. The mean oxygen uptake rate at 10 min was between 2.0 and 2.2 ml.kg-1 x min-1 in all groups. At 30 min the mean oxygen uptake rates were 2.6 to 2.8 ml.kg-1 x min-1. Carbon dioxide elimination was closely associated with expired minute ventilation, with a carbon dioxide excretion of about 30 ml per litre gas exhaled, irrespective of ventilatory mode employed.

Adult↗
PubMed1993

Complement and leukocyte activation in septic baboons.

The effect of Escherichia coli infusion on complement and leukocytes was evaluated in a baboon model. During 8 hr, different amounts of live E. coli (5 x 10(8), 2.5 x 10(9) and 10(10) live bacteria kg body weight) were infused. Twenty-one baboons were investigated. Activation of complement (terminal C5b-9 complement complex; TCC) and activation of leukocytes (PMN elastase) and plasma concentrations of endotoxin (lipopolysaccharide; LPS) were determined before the start of bacteria infusion and 2, 4, 6, and 8 hr after the start of infusion. In baboons receiving 2.5 x 10(9) and 10(10) live E. coli per kilogram body weight, increasing plasma levels of TCC were found (P < 0.05). No significant alterations of TCC were observed when animals were infused with 5 x 10(8) live E. coli per kilogram body weight during an 8 hr period. Plasma levels of PMN elastase increased significantly in baboons receiving 5 x 10(8), 2.5 x 10(9), and 10(10) live bacteria per kilogram body weight. High levels of LPS were detected in animals receiving 10(10) live E. coli bacteria per kilogram body weight and in animals receiving 5 x 10(8) or 2.5 x 10(9) live E. coli bacteria per kilogram body weight. There was a positive correlation between the formation of TCC and the plasma levels of PMN elastase and LPS and between plasma levels of PMN elastase and of LPS. Activation of complement and leukocytes may contribute to the development of organ dysfunction seen in baboons infused with high amounts of live E. coli.

Animals↗
PubMed1992

Isolated hyperthermic liver perfusion with cytostatic-containing perfusate activates the complement cascade.

Eight patients with advanced liver malignancy undergoing isolated hyperthermic liver perfusion with melphalan and cisplatin were studied with regard to complement activation and formation of anaphylatoxins (C3a and C5a) and terminal C5b-9 complement complexes (TCCs). Blood samples for complement variables (C1-INH, C3, C4, C5, C3a, C5a and TCCs) were taken before surgery, 1 min before the start of perfusion, 1, 2 and 3 h after the start of perfusion, and 24 h after operation. Samples were drawn from the perfusate 1 h after the start of perfusion. Activation of complement was observed during perfusion. Raised plasma concentrations of C3a and TCCs were recorded and high levels of C3a and TCCs were found in the perfusate. In vitro tests indicated that melphalan and cisplatin may activate complement. This activation occurred at 37 and 42 degrees C but was more pronounced at 42 degrees C.

Adult↗
PubMed1992

Inspiratory to end-tidal oxygen difference during nitrous oxide anaesthesia.

In order to evaluate the value of the inspiratory to end-tidal oxygen concentration difference (Io2-E'o2) as a monitor during general anaesthesia, we studied 40 orthopaedic patients allocated randomly to four groups: anaesthesia with enflurane or isoflurane in nitrous oxide with either spontaneous or controlled ventilation. (Io2-E'o2) followed an asymptotically increasing curve because of decreasing uptake of nitrous oxide. At 1 h, (Io2-E'o2) approached the end-tidal carbon dioxide concentration (E'o2). During spontaneous ventilation, (Io2-E'o2) correlated best with E'co2. During controlled ventilation, there was a negative correlation between (Io2-E'o2) and nitrous oxide uptake rate. Changes in oxygen uptake rate were reflected in (Io2-E'o2), provided that the total ventilation volume was constant and the nitrous oxide uptake rate approached steady state conditions.

Adult↗
PubMed1992

Living with fibromyalgia. Consequences for everyday life.

The influence of chronic pain on daily life was studied in 58 patients (55 women and three men) with fibromyalgia. The mean age was 45 +/- 11 (SD) years. A mail questionnaire including a 2-day diary was used for data collection. Information was gathered on social background, employment status, symptoms, physical training habits, patients' experience of general health, physical condition, and difficulties in performing motor tasks. The patient reported every half hour in the activity diary the degree of pain and fatigue, whether the activities were difficult to perform, and whether the patient considered them to be enjoyable, valuable, and meaningful. Fifty-five percent of the group had gainful employment. Most were working shorter hours and with changed work tasks. Motor tasks, such as carrying, holding, and running were more difficult to perform than before the onset of the symptoms, and half of the group reported most of their activities as strenuous to perform. Thirty-nine persons (67%) reported no, or very short, pain-free periods during the 2 days. In conclusion, symptoms influenced daily life considerably, and almost all patients reported changes in habits and routines as a consequence of fibromyalgia. An assessment of the patient's total life situation gives valuable information for understanding the patients' ability to handle everyday life.

Activities of Daily Living↗
PubMed1992

Uptake of enflurane and isoflurane during spontaneous and controlled ventilation.

The uptake of enflurane and of isoflurane were studied in forty patients during anaesthesia with nitrous oxide using either spontaneous or controlled ventilation. A Douglas bag method was used in combination with low fresh gas flows to a circle system and constant end-tidal anaesthetic concentration. The mean enflurane uptake rates were between 24 and 14 ml.70kg-1.min-1 between 10 and 60 minutes. Corresponding isoflurane uptake rates were between 15 and 8 ml. 70 kg-1.min-1. The initial uptake rates were lower than expected from "the square root of time concept". During spontaneous ventilation, the anaesthetic uptake rates were similar or even higher than corresponding rates during controlled ventilation in spite of lower minute ventilation volumes.

Adult↗
PubMed1992

Intestinal symptoms and serological response in patients with complicated and uncomplicated Yersinia enterocolitica infections.

Clinical course, serological response and effect of antibiotic treatment were evaluated in 34 patients with uncomplicated enterocolitis and in 27 patients with reactive arthritis (ReA) due to Yersinia enterocolitica. Patients participating in this prospective multicentre trial were randomised to treatment or no treatment with antibiotics. Only 3 (11%) of the patients who later developed ReA asked for medical care because of intestinal symptoms and fever and they all developed arthritis within 2 days after admission to hospital, i.e. before an etiological diagnosis was obtained. Patients with ReA had a history of milder intestinal symptoms than patients with uncomplicated enterocolitis. The peak IgA titer to Y. enterocolitica, as measured by enzyme linked immunosorbent assay, was higher in ReA patients and it was not affected by the presence of HLA-B27 antigen. On the other hand, untreated patients with uncomplicated enterocolitis had the longest duration of IgG antibodies. The duration of IgG antibody response was shortened in uncomplicated enterocolitis patients treated with antibiotics, but not in ReA patients. Treatment did not influence intestinal or ReA symptoms. It is concluded, that patients with uncomplicated enterocolitis due to Y. enterocolitica differ in intestinal symptoms and serological response, compared with patients who develop ReA. These parameters could however not be used to predict the development of arthritis in individual patients.

Abdominal Pain↗